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Title: Insect pests of the avocado and their control
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Title: Insect pests of the avocado and their control
Physical Description: Book
Creator: Wolfenbarger, D. O.
Publisher: University of Florida, Agricultural Experiment Stations
Publication Date: 1963
Copyright Date: 1963
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Bibliographic ID: UF00026912
Volume ID: VID00001
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Table of Contents
    Copyright
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Full Text





HISTORIC NOTE



The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida

























A A






INSECT PESTS OF THE AVOCADO
AND THEIR CONTROL
D. O. WOLFENBARGER

University of Florida
AGRICULTURAL EXPERIMENT STATIONS
J. R. Beckenbach, Director, Gainesville, Florida












SUGGESTED CONTROL PROGRAM'




December, January and February-
Apply miticide for avocado red mite control, page 17.
Cut out and destroy larvae of the avocado tree girdler,
page 37.

January, February and March-
Apply control measures for bloom infesting insects,
pages 29, 30, 31, 32.

May, June and July-
Cut out and destroy larvae of the avocado tree girdler,
page 37.
Apply treatment for scale insects, mealybugs or insect
infestations on fruit, pages 20, 21, 27.

August, September and October-
Apply treatments for control of the greenhouse thrips,
page 44.
Apply treatments for control of fruit scarring worms,
page 46.




1Suggested program only. Owing to the variability of the onset and
development of harmful infestations it is necessary to determine whether
pesticidal treatments are needed. It is not only unnecessary but wasteful
or even harmful on occasions to apply insecticides unless they are needed.






Fig. 1.-Damage caused by granulate cutworm feeding on
lower leaves of newly planted avocado tree.











CONTENTS
Page
SUGGESTED CONTROL PROGRAM ----. ----........ ..........-...--..- ..........-- 2
RESIDUES AND TOLERANCES ......----.......-- ... ---....---....-- ...--- ..--- 4
INSECT PESTS OF THE AVOCADO .....-.....-...................-.................-..---- 5
TYPE OF DAMAGE, INSECT RESPONSIBLE, CHART ....---...--.......--- ..-...-- ...-- 6
LEAF DAMAGE ........--...--...-....-- .............--- -.........-- ..... ......... ......... -........- 8
Whole Leaf Damage ..........-----.--....... ..-....-..-----...........-.... ...----... 8
Avocado Leaf Roller ....-.--- -.. --. ....-- ........................-- ....--- ..--- 8
Cutworms and Other Caterpillars .....---.....---...---............----.. 8
Banded Cucumber Beetle ..-....-----........-- ..-- ............---- ....-- 11
Bagworm .........----..--............- ............ ......------......-- ...--....----- 13
Grasshoppers .---..... -.....-...--......-- .......--- ..--- ...-- ....-- -.---. 13
Citrus Root W eevil .-...........--..........-. .....---........---..-----.. 15
Upper Leaf Damage ..........--........--....... ......--.....--... --------. 17
Avocado Red Mite ..........-................. .....---...........-- ----- 17
Red-banded Thrips ............--................---.- .. --------------17
Avocado Lace Bug ....--............. ............... ...--------- ---19
Florida Wax Scale --.......--...--------------...........----------------. 19
Florida Red Scale ....--........--.....-.........---....-- ..-- ----- 21
Lower Leaf Damage .....--------....................--.-..--.. ... ........... 22
Avocado Whitefly .------. --- ----............-........................ ------------ 22
Latania Scale ...........---. ...-....... ............-------------------......... ---22
Pyriform Scale .. --. -- --...........--.............----------... .........----23
Avocado Leafhopper -....--....--..------ .-.......----....--....... -----. 23
Mealybug ....- .--........--.......---.......... ----................................. 26
BUD DAMAGE --........... ------------ -----........ ..---................................... 29
Avocado Tree Girdler ...-......-.....--......-.--.. ....-- -........--- 29
BLOOM DAMAGE .- ----.... ...........--..........--...................................... ... 29
M irids ......-----.... .......... ..-- -- .. ............................................. 29
W ebbing W orms ...----... ---...............................-- ............... 30
Avocado Tree Girdler .- --......-- ....------.......- ---..........--- .......-- 31
Blossom Anomala ...-...-- ...--- ..........------ ..........-- .........-....... ..... ...... 31
Pumpkin Bug .--------.......--------... .... -... ---..............-.......... ...... ...... 32
TWIG AND BRANCH DAMAGE .--.............-------..................----------- 33
Dictyospermum Scale ........-----.......----...........................-...... 33
Ambrosia Beetle --.----.......-- --.............-..---------..........-- 35
TRUNK DAMAGE ----........... ---... ................................ .................... 36
Avocado Tree Girdler .---.........-..-- ............... ..-..........-...... 36
Termites ..... .---------.. ----........----................. ............. --38
ROOT DAMAGE .-------...------...-----.... .. .... ---................ ----40
Avocado Tree Girdler ..... ----..--...--........-..........-- ----.-.... .. -40
Little Fire Ant ..--.......-- ------- ........ .........-----------....... 40
FRUIT DAMAGE ............... ... .-...... ------............................. ........... -41
Small, Very Young .......--- ................-.--...........-....... .......... .... 41
M irids ................. ------------..................-....-..................................- .. 41
W ebbing Caterpillars ...--... ............................------------- --............... ... 41
Citrus Root Weevil ......----............-------..............-....---- .......- ....... 41
Avocado Tree Girdler ..----......-----------.-........ --............-...----........ ... 42
Large (More than % Inch in Diameter) Maturing ............................... 43
Greenhouse Thrips .-- ------.....--- -- --------................ ............................... 43
Fruit Scarring W orms ....-----........--... ................ ..... ................... 45
Pumpkin Bug --- --------------.... --- ---.... .. ................ -----..... .............. 46
Bagworm .----.... ..... ---........ ------------------.......................... ...... ..... 47
SOOTY MOLD ........... .............. ----------------.........---------- ...-..... 48
INSECTS INJURING OR ANNOYING TO GROVE WORKMEN .---.....--.......-....... 49
Wasps ----------------------------------------...................... 49
Mosquitoes -- ---.....- ------........................... -------........................... 50
MIXING, TIMING AND APPLICATION OF SPRAYS ......................- ------............ 51
AVOCADO PESTICIDE RECORD ------.--........ --. --.. ......-..................... 52











RESIDUES AND TOLERANCES

The U.S. Food and Drug Administration has established
tolerances on amounts of certain pesticide residues that can re-
main on avocado fruit. These are given in the chart below along
with recommended waiting periods between last application and
harvest.
Tolerances and waiting periods as of March 1, 1963 for
materials recommended in this bulletin follow:


TOLERANCE MINIMUM DAYS
PESTICIDE (PPM) BEFORE HARVEST

Benzene Hexachloride (BHC) 5 Use just before blossoming
or just after fruit set
DDT 7 30 days
Lead Arsenate 7 (Combined Remove excess residues at
Lead) harvest time
Lindane 10 Use just before blossoming
or just after fruit set
Malathion 8 7 days
Nicotine Sulfate 2 (Nicotine) No time limitations
Oil Emulsion Exempt No time limitations
Parathion 1 21 days
Sulfur, Wettable No time limitations
Sulfur, Dust No time limitations

"* These materials are generally recognized as safe and require no limiting tolerances when
used as recommended.

PRECAUTIONS
Insecticides are poisons and should be handled as such. Read
the label on each pesticide container before each use and heed
all cautions and warnings. Store pesticides securely in original
labeled containers away from food and feed. Dispose of empty
containers safely.
Parathion is especially toxic and is not recommended for
dooryard avocado trees.









INSECT PESTS OF THE AVOCADO
AND THEIR CONTROL

D. O. WOLFENBARGER 1

All avocado grove owners or grove caretakers should be
familiar with insect pests infesting the roots, branches, twigs,
leaves, buds, flowers and fruit of avocados. About a fourth of
the two dozen insect and mite species attacking Florida avocados
have an important economic status.
A given pest may be serious for a season, then subside for a
decade or more. This is shown by the red-banded thrips, Seleno-
thrips rubrocinctus (Giard) which caused much defoliation of
trees in 1947-48 but has been of little importance since then.
The avocado lace-bug, Acysta perseae Heid., has been practically
unseen for decades and is unknown to most avocado growers to-
day. The most common pest is the avocado red mite, Oligo-
nychus yothersi (McG.) which is harmful in some groves each
year, in other groves periodically, and is seldom observed in
some groves. Comparative freedom from insect pests reduces
the frequency, amount of damages sustained and expenses for
control measures, but should not reduce the vigilance and con-
stant observations necessary to detect the rise of an important
pest. Much variation is found in the species and abundance of
a given species of harmful insect pests. The pests are probably
present in very low numbers at all times and may escape notice,
but may appear in abundance when condition become favorable.
Climatic and other factors bring about conditions favoring
avocado insect pest increases and decreases. These factors, their
interrelationships and their effects on insect abundance are not
fully understood at present. It is not possible to make satisfac-
tory prediction as to when these pests will appear, nor the
extent of their damage.
Damage caused by pests is usually slight and inconspicuous
at the outset of a serious infestation. Damage from only a few
insects is also slight and often inconspicuous, and economically
it is unwise to apply insecticides to control a few insects. The
avocado leaf roller, Gracilaria perseae Busck, for example, is
present in low numbers practically all year. Treatments for its
control would require many repetitions and likely would not re-
SEntomologist, Subtropical Experiment Station, Homestead, Fla.







TABLE 1.-CHART INDICATING PART OF TREE INJURED OR AFFECTED, MONTH
OF LIKELY APPEARANCE, AND PAGE OF DISCUSSION.
LEAF DAMAGE
WHOLE LEAF DAMAGE Page
Avocado leaf roller............ Mostly spring and summer ............................ 8
Cutworms and other
caterpillars ...................... Mostly spring and summer ........-................... 8
Banded cucumber beetle-. Summer months ......................... ----............- .. 11
Bagworm ............................. All months, more abundant in winter ............ 13
Grasshoppers ..................... Summer months ..........................---- ......... .......... 13
Citrus root weevil ........... Early spring months .....................-..........-........ 15
UPPER LEAF DAMAGE
Avocado red mite ............. December, January, February ..........-................. 17
Red-banded thrips ........... September, October, November ........................ 17
Avocado lace bug ............ W inter months .........................-- .........- ........-. 19
Florida wax scale ............ W inter months .......-.................. --................ ---- 19
Florida red scale ............ All months of the year .................................. 21
LOWER LEAF DAMAGE
Avocado whitefly ...........-.... Summer and fall months ............................... 22
Latania scale .............-........ Fall, early winter ............-....... .................. .. 22
Pyriform scale ........-----..... Summer, fall, early winter ............................... 23
Avocado leafhopper .-...... Summer, fall, and winter .................-.............-... 23
M ealybug --............-- ...-- ... ... Summer, early fall ................--........... ........ 26
BUD DAMAGE
Avocado tree girdler ........ All months of the year .---........................---. 29
BLOOM DAMAGE
Mirids ......--- .................-- ...... February, March and April .-................... ... 29
Webbing worms ................ February, March and April ..-............--.......-... 30
Avocado tree girdler ........ February, March and April ......................-.... 31
Blossom anomala ............ February, March and April ..-........................ 31
Pumpkin bug ..................... February, March and April ..........-....-...-.....-.. 32
TWIG AND BRANCH DAMAGE
Dictyospermum scale ........ All months of the year .......... --....--.....-........ -- 33
Ambrosia beetles .......-....... Summer, early fall .....-...-..-......--.. .......-......... 35
TRUNK DAMAGE
Avocado tree girdler ........ All months of the year .............................--... 36
Termites .............................. All months of the year .....-----........................... 38
ROOT DAMAGE
Avocado tree girdler ........ All months of the year .--..-................-- ......... 40
Little fire ant .................... All months of the year ..------...- -............-... ... 40
FRUIT DAMAGE
SMALL, VERY YOUNG
Mirids ..................-............... February, March and April ........................... 41
Webbing caterpillars ........ February, March and April .-.....--...--........-.... 41
Citrus root weevil .............. Spring, early summer ....-.......-......................... 41
Avocado tree girdler ....... Spring, early summer ....--......--............-............ 42
LARGE, (MORE THAN
Y INCH IN DIAME-
TER) MATURING
Greenhouse thrips .............. August, September and October .........-- ..... 43
Fruit scarring worms ...... August, September, October, November........ 45
Pumpkin bug ...................... September, October, November, December .... 46
Bagworm .............................. Late summer, fall, early winter ................... 47
INSECTS INJURING OR ANNOYING GROVE WORKMEN
Wasps .......-----..-.....-.-... .. September, October, November & December.. 49
Mosquitoes --...----.....-...... June, July, August and September ............... 50







Insect Pests of the Avocado and Their Control 7

pay the cost. Successful management of groves to control in-
sect pests requires constant watchfulness to determine the on-
set of the damaging infestation and decide where effective treat-
ment is needed. Experience from past performances of insect
pests and good judgment concerning conditions at a given time
should be used in deciding on applications for control of a pest.
The grower should watch his trees carefully for insect pests and
apply remedies where they are needed.
Grove owners and managers with experience know when,
where and how to examine trees for insect pests, especially the
more common ones. Those with little or no experience often
need some assistance in learning procedures for examining their
trees for damaging insect pests. A very brief general descrip-
tion and control suggestions of the different pests are given
(Table 1), arranged according to the type of injury to the tree
and the time of year in which they usually appear. Many pesti-
cidal materials have label approval for use on avocados. Some
of the newer chemicals, although more effective than some of

Fig. 2.-Rolled terminals of avocado leaves caused by avocado leaf roller.













r 4- -






8 Florida Agricultural Experiment Stations

the older ones, have not been approved for use because of pos-
sible toxic residues. These cannot be recommended until they
have approval for use.

LEAF DAMAGE

WHOLE LEAF DAMAGE
Avocado Leaf Roller
Importance and Evidence of Infestation.-Larvae of the avo-
cado leaf roller, Gracilaria perseae Busck, feed on leaves and
undoubtedly cause considerable injury to the trees. Larvae
appear on new leaves throughout the year, which makes con-
trol more difficult and questionable from the economic viewpoint.
Holes and irregularly eaten areas in the terminal portions
of older leaves characterize avocado leaf roller feeding and give
a ragged appearance to severely infested trees. Twisted and
distorted leaf tips, which are rolled by the insect in the early
stages of growth, also are evidence of avocado leaf roller in-
festation (Fig. 2).
Description.-Eggs deposited by the adult on very small leaves
soon hatch and the larvae grow as the leaves grow. The insect
may feed as a leaf miner in the leaves or it may feed on leaf
surfaces. Larvae tie the leaf tips with silken strands and make
them roll, thus providing protection. Larvae are reddish or
greenish with indistinct horizontal stripes and grow to about
one-half inch in length. Larvae, at maturity, construct pupal
cases in a leaf roll or fold and emerge several days later as small
grayish colored moths.
Control.-Lead arsenate is the suggested control, although
benzene hexachloride and some other of the newer insecticides
are probably as effective. Three pounds of lead arsenate per
100 gallons of water is suggested. Combination of lead arsenate
with the fungicidal or nutritional spray works satisfactorily.

Cutworm and Other Caterpillars
Importance and Evidence of Infestation.-Newly planted
and mature trees are occasionally killed and others injured by
three or more species of larvae (Fig. 1, 3, 4, 5). An arctiid,
Seirarctia echo (A. & Sm.), and the granulate cutworm, Feltia
subterranea (F.) (formerly annexa (Treit.), were recognized







Insect Pests of the Avocado and Their Control 9

(determinations by J. G. Franclemont) by name; others have
not been reared and, therefore, are not known definitely by
name. Some small trees were killed; others were defoliated.
The arcitiid larvae fed visibly on leaves, twigs and bark. Cut-
worm larvae seek protection around the bases of plants during
daylight and emerge to feed after dark.
Description.-Arctiids, hairy, conspicuously yellow-banded






































Fig. 3.-A span-worm, Epinecis detexta Wlk, feeds on avocado leaves.





































Fig. 4.-Arctiid larvae feeding on leaves and terminal of a young tree.

Fig. 5.-Leaf-tier feeding, rolling and rubbing leaves of terminal branch.







Insect Pests of the Avocado and Their Control 11

larvae, 11/2 to 2 inches in length, feed in daylight hours. Smooth,
dull gray cutworm larvae about 11/2 to 2 inches long may be
found in daylight hours curled head-to-tail under stones, among
wood shavings mulch and in the soil. Variously colored, gray,
yellow, red and brown larvae may be found feeding on leaves.
Control.- Lead arsenate, 3 pounds per 100 gallons of water,
is recommended for application to tree foliage. DDT, 2 pounds
of 50% wettable powder per 100 gallons of water, may be used
on the ground around young trees. Younger stages of cutworm
larvae are easier to kill than older, more mature larvae. A 5%
DDT dust may be used instead of the spray. DDT is not recom-
mended for use on foliage because of probable scale and mite
build up.
Banded Cucumber Beetle
Importance and Evidence of Infestations.-The banded cu-
cumber beetle, Diabrotica balteata Lee., is a "general feeding"
insect and feeds occasionally on avocado trees. Such feeding
is generally limited to a few terminal branches in a grove. In-
juries are too few, as a rule, to justify treatment for control.
Newly developed leaves are attacked and remain as evidence of
pervious feeding until leaf-fall. Interveinal tissues and mar-
ginal and central portions are consumed (Fig. 6).





















Fig. 6.-Interveinal leaf feeding by banded cucumber beetle.








12 Florida Agricultural Experiment Stations















































Fig. 7.-Bagworms on tree terminal (arrows) showing defoliated
portion and also leaf feeding of larvae.







Insect Pests of the Avocado and Their Control 13

Description.-Greenish-yellow beetles with transverse bands
across the wing covers and about 1/2 inch in length may be
found in the leaves attacked. Larvae of this pest are soil-inhab-
iting insects which feed in plant roots, but they have not been
recognized as injurious to the avocado.
Control.-Parathion, 1 pound of 15% wettable powder per
100 gallons of water, is effective in control of the insect. Ben-
zene hexachloride, 2 pounds of 10% gamma-isomer wettable
powder per 100 gallons of water, may be used if it is desired to
avoid the use of parathion.

Bagworm
Importance and Evidence of Infestation.-Bagworm larvae,
Oiketicus abbotii Grt. (identified by Dr. F. J. Gates Clark), have
been of little economic importance to avocado groves in most
areas. In a grove on the muckland soils, however, trees were in-
fested generally and stripped of much of the leaf surfaces. These
larvae, although active and able to move about, live in silken
bags to which leaf and stem segments adhere and appear as
masses of dead and rolled leaves (Fig. 7). Leaves, bloom and
fruit are attacked. Leaves in the upper parts of trees are at-
tacked more frequently than those on the lower branches. In-
festations appear more frequently during seasons of more rapid
tree growth, but may be found all year.
Description.-Bags containing larvae attain lengths of 21/2
inches. Larvae are usually 1/2 to 11/ inches long and brown
with whitish markings. Moths are a brownish color, with wing
spreads of 1 to 2 inches and long pointed abdomens (Fig. 8).
Moths are seen less frequently than larvae.
Control.-Lead arsenate, 3 pounds per 100 gallons of water,
is suggested for those who wish to apply control measures.

Grasshoppers
Importance and Evidence of Infestation.-Consumption of
avocado leaves by grasshoppers, Chortophaga viridifasciata aus-
tralior R. & H. and Leptisma marginicollis (Seville), may be so
extensive that young trees are stunted or killed, especially new-
ly planted trees in older groves where grass and weed growth
are rank. Losses from grasshoppers, although common through-
out the year in small measures, are seldom of much importance.
Feeding by grasshoppers is evidenced by irregular patterns on







14 Florida Agricultural Experiment Stations

































Fi. 8.-Baworm adults pinnedd specimens enlarged about 2 times).






Insect Pests of the Avocado and Their Control 15

the leaf margins. Portions from the entire leaf surface may
be eaten indiscriminately.
Description.-The several grasshopper species that feed on
avocado leaves are usually between 1 and 11/2 inches in length
(Fig. 9). They have general overall colors of green, brown or
tan, marked with areas of lighter and darker pigments. These
insects usually hide beneath or behind leaves, so they are diffi-
cut to observe. The insects also jump and fly if one approaches
closely.






















Fig. 9.-Grasshopper nymph on new leaf growth. Feeding
indication on leaf at left. (About natural size.)

Control.-It is recommended that grass and weeds be sup-
pressed around the trees, especially the young or non-bearing
ones. For non-bearing trees apply benzene hexachloride or lin-
dane as for webbing worms, page 30. Parathion or malathion as
for red-banded thrips, page 17, is suggested for trees with fruit.

Citrus Root Weevil
Importance and Evidence of Infestation.-The citrus root
weevil, Pachnaeus litus (Germ.), is an insect often seen, but
is a pest of minor importance to the avocado. Adults are few






16 Florida Agricultural Experiment Stations

in number and are usually seen in the spring and early summer
months. They sometimes feed on blossoms, young fruit and
twigs (Fig. 10). It is likely that larvae feed on the roots, but
no apparent injury to avocado trees by larvae has been observed.
Semi-circular areas, characteristic of weevil feeding, are fre-
quent and beetles are often observed; larvae are seldom seen.



















.-Ol













Fig. 10.-Citrus root weevil on avocado twig (arrow), defoliation of
terminal, and leaf-feeding symptoms (opposite beetle).

Description.-Citrus root weevils vary from about /3 to 1/\
inch in length and have a snout, characteristic of the group.
They vary widely in color; most are bluish green, some are gray






Insect Pests of the Avocado and Their Control 17

slightly tinged with blue or green, others are gray or slightly
brownish.
Control.-These insects have not been of sufficient impor-
tance to warrant control measures. Benzene hexachloride, 2
pounds of 10% gamma-isomer wettable powder, or 1 pound
of 15% wettable powder of parathion per 100 gallons of water,
would be the suggested treatment.

UPPER LEAF DAMAGE

Avocado Red Mite
Importance and Evidence of Infestation.-Destruction or re-
moval of the green coloring material in avocado leaves by the
avocado red mite, Oligonychus yothersi (McG.), reduces tree
vitality and, in cases where the infestations are sufficiently
severe, there is heavy and premature leaf fall. During the dry
season, December to March, avocado leaves may become reddish
colored owing to mite infestations. Slight webbing by. the
mites, egg shell remnants and cast skins of the young are signs
of infestations and contribute to a dull, powdery, reddish-gray
color of the upper surfaces of leaves.
Description.-Adult mites are very small, 1/75-1/100 inch
long, and reddish in color (Fig. 11). Young mites hatch from
globular-shaped amber-colored eggs, generally placed along the
midribs of the upper leaf surfaces. Rapid increases in the pop-
ulations may occur since life cycles may be completed in 15
days.
Control.-Constant vigil is recommended during December,
January and February to ascertain that mite abundance remains
low. Control measures may be initiated when the population
reaches six or more mites per leaf. Sulfur dust, 4 to 8 ounces
per tree (40 pounds per acre), has given satisfactorily control.
Wettable sulfur, 10 pounds per 100 gallons of water, as a spray
covering the leaves also has given satisfactory mite control.
An oil emulsion spray made by mixing 3 quarts of 90-92% oil
per 100 gallons of water and applied thoroughly will control
these mites.
Red-Banded Thrips
Importance and Evidence of Infestation.-Red-banded thrips,
Selenothrips rubrocinctus (Giard), infest avocado, mango, guava
and other plants and feed on leaves and fruit. Thrips have







18 Florida Agricultural Experiment Stations

piercing and sucking mouth parts and occasionally may become
so abundant that trees lose their leaves, thus suffering loss of
vitality. Infested leaves are spotted on the upper surfaces with
dark red fecal deposits where the insects congregate and feed.
Leaf surfaces on which much feeding occurs become lighter
green and later brown. This extends until large areas of leaves
become brown, shivel and fall. Fruit where much feeding
occurs becomes russetted in appearance, cracked and decayed.






























Fig. 11.-Avocado red mites on avocado leaf; empty egg cases and
cast skins of mites are whitish objects (much enlarged) .

Description.-Adult thrips are black, have fringed wings and
are about 1/25 inch in length, similar in appearance to the
greenhouse thrips adults (Fig. 31). Nymphs are generally
yellowish in color, but have two red bands on the middle of the







Insect Pests of the Avocado and Their Control 19

abdomen (the source of the common name). The egg is trans-
parent, oval-shaped and approximately 1/100 inch in length and
is inserted in the leaf tissues. Nymphs hatch from the eggs and
begin feeding on the leaf. Two intermediate stages, the pre-
pupa and the pupa, are passed before the insect becomes an
adult. Insects in these stages are somewhat similar to the
nymphs in appearance, but are less active than nymphs and
adults.
Control.-Maintain observations during summer and fall for
any developing infestation. One pound of 15% parathion wet-
table powder or 3 pounds of 25% malathion wettable powder
or 1 pound of 25% lindane wettable powder or 1 pint of 40%
Nicotine sulfate liquid concentrate per 100 gallons of water is
suggested for control.

Avocado Lace Bug
Importance and Evidence of Infestation.-Trees have been
rarely infested with the avocado lace bug, Acysta perseae Heid.,
within the last decade. Infested trees in one grove, however,
were partly defoliated and suffered minor injuries. Yellowish
or brownish colored leaf areas and the presence of reddish brown
bugs and excreta on the underside of the leaves are evidence of
infestations (Fig. 12).
Description.-Colonies of the reddish to brownish-black bugs,
the adults of which have "lacy" appearing wings, may be found
on the under leaf surface. Adults are about 1/12 inch long and
usually seen on the leaves among nymphs, which are less than
1/2 inch long, eggs and excreta in reddish brown colored areas.
Control.-Benzene hexachloride, parathion and nicotine sul-
fate are suggested insecticides. The amounts suggested per 100
gallons of water are: Benzene hexachloride, 2 pounds, 10%
gamma-isomer; parathion, 1 pound; 15% wettable powder and
nicotine sulfate, 1 pint 40% combined with 2 liquid ounces of a
wetting or spreading agent.

Florida Wax Scale
Importance and Evidence of Infestation.-Florida wax scale,
Ceroplastes floridensis Comst. (Fig. 13), is a common but not a
serious pest of the avocado, owing perhaps to the high degree
of its parasitization. Presence of waxy covered specimens is







20 Florida Agricultural Experiment Stations

evidence of infestation although the presence of sooty mold
may indicate the Florida wax scale or other insect (see p. 47).
Description.-Dirty white to occasional pinkish tinted speci-
mens on the upper leaf surfaces are outstanding in appearance.
The scales are nearly circular, very nearly convex, about 1/9-
1/14 inch in diameter.
Control.-Control of the Florida wax scale is apparently more
difficult than that of other soft scales. A spray application of
11/3 gallons of emulsive oil combined with parathion, 11/2 pounds
of 15 % wettable powder per 100 gallons of water was very effec-
tive.
Fig. 12.-Avocado lace bugs on under side of leaf.
Nymphs, adults, eggs and excrement are intermingled.





40 s "-





*1J* '
%V 1 A-













.. -

Vgti


A '/s i







Insect Pests of the Avocado and Their Control 21





































Fig. 13.-Florida wax scales on upper leaf surface along midrib
(much enlarged).

Florida Red Scale
Importance and Evidence of Infestation.-The Florida red
scale, Chrysomphalus aonidium (Linn.), infests avocado leaves
(upper and lower surfaces), twigs, stems and fruit. It is not
of importance in avocado production. This scale occurs more
often on the upper leaf surfaces, seen as dark reddish spots.







22 Florida Agricultural Experiment Stations

Description.-The Florida red scale is circular, slightly con-
vex and about 1/14 inch in diameter. It is dark reddish brown,
almost black. It is similar to the dictyospermum scale except
that it is very slightly larger and more reddish brown in color.
Control.-Owing to the lack of importance on the avocado,
there is seldom any need for control measures. Parathion, 11/2
pounds of 15% wettable powder, oil 1 to 11/3 gallons of emulsive
oil or a combination of parathion, 1 pound 15% wettable powder
and 1 gallon of emulsive oil per 100 gallons of water is the rec-
ommendation for control of the scale.

LOWER LEAF DAMAGE
Avocado Whitefly
Importance and Evidence of Infestation.-Dense populations
of the avocado whitefly, Trialeurodes floridensis (Quaint.),
cause distorted and malformed leaves. There appears to be an
expansion of the interveinal leaf tissues, caused by the whitefly
feeding, that makes leaf surfaces unequal. Whitefly infesta-
tions give rise to unthrifty leaves and stems of trees and un-
sightly black sooty mold (see p. 48) on leaves, stems and fruit.
The whitefly, however, is ordinarily of little importance in com-
mercial groves. Infestations are first found on the underside
of new leaves. Adults (winged form), pupae and nymphs
(crawler form) are evidences of infestation. Black sooty mold
is a sign of infestation of whiteflies, aphids, scale insects or
mealybugs. Whitefly infestations are usually more frequent
and abundant whenever trees are growing rapidly.
Description.-The avocado whitefly is about 1/10 inch long,
with a pale yellowish body and white wings. Pupae have a char-
acteristic fringe of waxy filaments about the margins of the
body. Nymphs, very pale yellowish colored creatures, are about
1/25 inch across and hatch from white eggs.
Control.-Emulsive oil concentrate, 11/4 gallons per 100
gallons of spray, or 1 gallon of oil combined with parathion 1
pound of 15% wettable per 100 gallons of spray, is a recommend-
ed spray control measure.

Latania Scale
Importance,and Evidence of Infestation.-The latania scale,
Aspidiotus lataniae Sig., is very prevalent on the undersides of







Insect Pests of the Avocado and Their Control 23

leaves, especially in late fall and winter seasons. Twigs, branches
and fruit are infested, but leaf infestations attract most atten-
tion. Since the lower leaves are those most heavily infested and
these in the late life of the leaves, the insect is not a serious pest.
Masses of dirty white to light yellowish scales are usual evi-
dences of infestations.
Description.-Circular rather convex armor coverings of the
latania scale are about 1/20 to 1/15 inch in diameter. Central
areas of the scale are usually slightly darker than the marginal
areas. Yellow eggs beneath the scale hatch into yellowish crawl-
ers which settle nearby, feed and begin secretion of the armor
covering.
Control.-Parasites usually prevent concentrations of the
latania scale so that chemical application for control is unnec-
essary. Oil emulsion, 1 to 11/ gallons actual oil, or /4 to 1 gallon
emulsive oil combined with parathion, 1 pound 15% wettable
powder or 3 pounds of 25% wettable powder, per 100 gallons
of water is recommended if an insecticidal treatment appears
necessary.
Pyriform Scale
Importance and Evidence of Infestation.-Feeding by the
pyriform scale, Protopulvinaria pyriformis (Ckll), (Fig. 14)
reduces the tree vitality and the excretion of honeydew followed
by the development of black fruit (see p. 48). Scales with
white cottony masses under some individuals indicate infesta-
tions.
Description.-Triangular or pear-shaped flattened pyriform
scales are light greenish brown to brown. They are about 1/
inch long to 1/10 inch wide. A white cottony appearing mass,
the egg sac extends from underneath (the female) scales.
Control.-Emulsive oil, parathion or malathion will give con-
trol of the pyriform scale. One to 11/3 gallons of oil alone;
parathion, 1 pound of 15% wettable powder or malathion 4
pounds of 25% wettable powder, per 100 gallons of water gives
control of the scale.

Avocado Leafhopper
Importance and Evidence of Infestation.-Removal or de-
struction of the green coloring of the leaves by the avocado
leafhopper, Idona minuenda (Ball), seen in "whitened" areas,







24 Florida Agricultural Experiment Stations

may result in unthrifty trees. Usually the avocado leafhopper
remains at low population levels and is of little importance to
commercial groves, although it is commonly present in small
numbers. Areas of whitened leaf surfaces are symptomatic of
avocado leafhopper infestation. Leaves containing leafhoppers,
whitened tissues and cast skins on the undersides of leaves are
evidences of infestation.





































Fig. 14.-Pyriform scale insects on lower leaf surface of avocado
(slightly enlarged).







Insect Pests of the Avocado and Their Control 25













.. - ...






















Description.-Adults and nymphs are light green, similar
to the leaves (Fig. 15). Adults have very pale green wings and
are about 1/10 inch in length. Insects may remain motionless
on the leaves or they may run or fly rapidly when disturbed.
Control.-Parathion and malathion ordinarily give excellent
control of leafhoppers. Rates of application per 100 gallons of
control of leafhoppers. Rates of application per 100 gallons of







26 Florida Agricultural Experiment Stations

water suggested are: Parathion, 1 pound of 15% wettable
powder or /2 pint of emulsion concentrate (4 pounds per gallon) ;
or malathion, 4 pounds 25% wettable powder or 1 quart of 50%
emulsifiable. Dust mixtures, 1% parathion or 5% malathion
at 40 pounds per acre also are suggested.

Mealybug

Importance and Evidence of Infestation.-Mealybugs, such
as the citrus mealybug, Pseudococcus citri (Risso) (Fig. 16),
are occasionally abundant on avocados, especially in summer.
These sucking insects take nourishment from the stems, fruit
and leaves, and may be of considerable importance if abundant.
Black sooty mold covering fruit, leaves and branches, resulting
from mealybug secretion, however, may be more immediately
important than crop reduction or tree vitality losses, by giving
fruit an unsightly appearance.
Description.-White, powdery, cottony masses covering the
light amber-colored, oval-shaped insects characterize mealybug

Fig. 16.-Coconut mealybug infestation on twig and leaves.









., mmm~~; ~5:







Insect Pests of the Avocado and Their Control 27

infestations. Although wax secretions around the edges of the
insect bodies make them appear larger, lengths vary from 1/10
to 1/6 inch.
Control.-Although the mealybug is seldom so abundant that
control measures are needed, occasionally insect reductions are
necessary. "Spot" spraying of infested trees is recommended,
unless the insect is generally abundant. Parathion, 11/2 to 2
pounds of 15% wettable powder or malathion, 4 pounds of 25%
wettable powder per 100 gallons of water, will control mealy-
bugs.


































Fig. 17.-Dead twigs, buds and branches caused by
feeding of adult avocado tree girdler.







28 Florida Agricultural Experiment Stations

















































Fig. 18.-Multiple branching and enlarged growth from repeated bud
destruction by the avocado tree girdler (about natural size).







Insect Pests of the Avocado and Their Control 29

BUD DAMAGE
Avocado Tree Girdler
Importance and Evidence of Infestation.-The adult avocado
tree girdler, Heilipus apiatus Oliv., as stated above, feeds
on the buds. Such feeding is often severe (Fig. 17) and is more
frequent than feeding on twigs and branches. Destruction of
the normal buds causes the development of secondary buds. If
these secondary or later buds are destroyed as by infestations
of great severity, still others are produced, some of which may
develop into twigs. Clubbed or knobby developments may occur
and deform or stunt twig development (Fig. 18). Beetles and
characteristic beetle feeding wounds and scars are evidences
of infestations.
Description.-Description may be found on page 37.
Control.-See under Bloom Damaging Insects.

BLOOM DAMAGE
Mirids
Importance and Evidence of Infestation.-These small plant
bugs feed (Fig. 19) on flower clusters, expanding buds and
young fruit, causing them to fall. Mirid species taken from
avocado bloom were Lygus fasciatus var. olivaceous Reuter, L.
fasciatus var. viridisculus Kngt. and Lepidopsallus pusillus Kngt.
Specimens of Polymerus cuneatus (Distant) and Reuteroscopus
ornatus (Reuter) were also taken. These bugs, which are usually
present on Spanish needle or other plants under the trees most
of the season, move to the expanding buds, blossoms and young
fruit in the spring. These insects are usually so few in number
that they are of no great economic importance and ordinarily
require no insecticidal treatment.
Description.-These insects are comparatively small, possess
colors that blend with their surroundings and elude observers.
Most of the bugs are about 1/8 inch in length. Color patterns
are a variety of mixtures of green and brown. These bugs hide
behind stems, blossom pedicels and other plant structures. When
the insects are disturbed they fly, making them more difficult
to observe.
Control.-Make periodical examinations during the blooming
period to determine the abundance of mirids, especially toward







30 Florida Agricultural Experiment Stations
























Fig. 19.-Mirids that infest avocado bloom. (Enlarged about five times.)

the end of blooming period and early fruit development. If more
than three mirids per blossom cluster are found, control meas-
ures are recommended. Benzene hexachloride, 2 pounds of 10%
gamma-isomer per 100 gallons of water, has given excellent mirid
control.
Webbing Worms
Importance and Evidence of Infestation.-A web-spinning
caterpillar, Argyrotaenia amatana (Dyar), infests buds and
bloom clusters, feeds and destroys buds, blooms and leaves.
Other species of caterpillars also have been recognized (but
not positively identified) in bloom clusters. Fruit production
is reduced where the insects are numerous. An outstanding
characteristic of infestation is masses of bloom and medical
debris webbed together.
Description.-Dark, grayish greenish to brownish larvae with
indistinct black markings may be found in the webbing. These
larvae are 1/2 to 1 inch long and wriggle actively to escape loca-
tion. Adults of Argyrotaenia amatana have reddish brown
wings that are seldom observed.







Insect Pests of the Avocado and Their Control 31

Control.-lead arsenate, 3 pounds per 100 gallons of water,
is recommended for control. Benzene hexachloride, 2 pounds
of 10% gamma-isomer wettable powder; lindane 1 pound of
25% gamma-isomer wettable powder, parathion 1 pound 15%
wettable powder, or malathion, 3 pounds 25% per 100 gallons
of water should give satisfactory control.

Avocado Tree Girdler
Importance and Evidence of Infestation.-Adults of the avo-
cado tree girdler, Heilipus apiatus Oliv., feed on buds, bloom
and bloom pedicels, as well as other parts of the avocado plant.
Such feeding reduces fruit production. The amount of reduction
depends on the beetle population. Blossoms which have been
cut from the pedicel may suggest the presence of the H. apiatus
or of the Anomala undulata (see below). It becomes neces-
sary, therefore, to find the beetles on the tree in order to ascer-
tain the insect involved.
Description.-Description is given on page 37 under Insects
Damaging Tree Tunks.
Control.-Beetles are generally too few for the need of any
chemical control efforts. If they are sufficiently abundant to
justify treatment, a number of insecticides may be used. Lab-
oratory tests have shown that a number of insecticides applied
to beetles and foliage were effective. They include benzene
hexachloride, 2 pounds, 10% gamma-isomer wettable powder
lindane, 1 pound 25% gamma-isomer wettable powder and par-
athion 1 pound, 15% wettable powder per 100 gallons of water.

Blossom Anomala
Importance and Evidence of Infestation.-Swarms of the noc-
turnal feeding blossom anomala, Anomala undulata Mels., may
cause serious damage by feeding on the bloom. Such damage
has not been observed by nor reported to this writer within the
last decade. These beetles infest the bloom. Many blossoms
cut by the beetles may litter the ground beneath the trees and
indicate beetle feeding.
Description.-The beetles are about 1/4 inch long and have
a black thorax with yellowish borders and brownish wing cov-
ers. Some beetles may be almost black.







32 Florida Agricultural Experiment Stations

Control.-Several of the newer insecticides should give ex-
cellent control of this insect. It is suggested that the following
materials be used per 100 gallons of water: Benzene hexachlor-
ide, 2 pounds, 10% gamma-isomer wettable powder; parathion,
1 pound, 15% wettable powder.

Pumpkin Bug
Importance and Evidence of Infestation.-The pumpkin bug,
Nezara viridula (L.), which feeds on many plants may be found
among avocado bloom (Fig. 20). It has not appeared in suffi-
cient numbers to indicate that it is important on avocado bloom.
Description.-See page 47.
Control.-See page 47.































Fig. 20.-Pumpkin bug feeding on avocado bloom (enlarged).







Insect Pests of the Avocado and Their Control 33

TWIG AND BRANCH DAMAGE

Dictyospermum Scale
Importance and Evidence of Infestation.-Dictyospermum
scale, Chrysomphalus dictyospermi (Morg.) (Fig. 21), is one
of the more common scales affecting the avocado. It is fre-
quently more injurious to young, two to five year old trees,
than to older trees. Older trees of some varieties, however,
Lula for example, are often severely injured. Defoliation and
death of trees and branches may result from dictyospermum
scale infestations. Evidence of dictyospermum scale infesta-
tion is observed more commonly at or near crotches of small
trees and branches. Blackened areas often with a glossy or
"greasy" appearance are symptomatic of infestations. Scale
infestations are usually more abundant in the late summer or
early fall and less abundant shortly after the blossoming period.
Black sooty mold develops on fruit, leaves, stems and trees in-
fested with the dictyospermum scale (see p. 48).
Description.-Dictyospermum scale insects are flattened
against leaf or bark surfaces, are circular or oval in shape and
are less than 1/10 inch in diameter. Adults are observed usual-
ly, and they remain fast on the spot where the young insect
(crawler) first began feeding. Scales are present throughout
the year, but are apparently more numerous in late summer
and fall.
Control.-An oil and parathion combination, 1 gallon of emul-
sifiable oil concentrate and parathion, 1 pound of 15% wettable
powder per 100 gallons of spray, is effective in scale control on
avocados. Emulsifiable oil at 11/3 to 11/2 gallons per 100 gallons
of spray is also effective in scale control. This amount of oil
tends to "shock" the trees, and it may injure or defoliate trees
if applied in a very dry period, during hot weather (900 F.) or
just preceding or during a cold spell (300-35o F.). Parathion
at 11/2 pounds of 15% wettable powder per 100 gallons of water
is satisfactory for scale control. Malathion may be used for
scale control at 4 to 5 pounds of 25% wettable powder per 100
gallons of water. It may be combined with oil emulsion for in-
creased effectiveness. Parathion or malathion, applied alone
during the dry or winter season, often gives rise to injurious
infestations of avocado red mites. Emulsifiable oil or sulfur may
be combined with the phosphatic materials for mite and scale








34 Florida Agricultural Experiment Stations






















"I.c,
































Fig. 21.-Distyospermum scale on avocado twigs. Massed scales are
near top of center twig. In lower right corner are three scales greatly
enlarged.







Insect Pests of the Avocado and Their Control 35

control however, oil emulsion and sulfur should never be com-
bined. These materials should neither precede nor follow the
other for three weeks.

Ambrosia Beetle
Importance and Evidence of Infestation.-Ambrosia beetles,
Xylosandrus sp. or other genera, burrow into tree trunks, stems,
branches and twigs. Infested trees and branches are unthrifty
at the time of attack, but frequently appear to have been healthy
and vigorous. Fungi accompany the beetles and develop mycelia
in tree tissues, which constricts branches and trees. As a result








4. -
























Fig. 22.-Ambrosia beetle entrances in small twigs. Crystalline sap
deposits frequently surround beetle gallery entrances.







36 Florida Agricultural Experiment Stations

the portion of the tree terminal to the burrow entrance usually
dies. Although infestations are usually not numerous, they have
been serious in some nurseries and young groves. White crys-
tals of sap about the burrow entrances are evidence of infesta-
tion (Fig. 22). Infestations are usually in shaded portions of
trees, frequently on the undersides of branches. These insects
hasten death and decay of weakened branches and kill some
trees, but are not considered a serious threat to well-kept groves.
Infestations appear more frequently in early- to mid-summer.
Description.-Beetles are brownish to almost black and small,
about 1/50 inch in diameter and 1/20 inch long. Eggs and
young of the beetles are white and are found in the galleries.
Larvae feed on the mycelia of "ambrosia" fungi growing in the
galleries.
Control.-Removing and burning infested tree parts is rec-
ommended. Spray applications of benzene hexachloride, 2
pounds of 10% gamma-isomer or its equivalent per 100 gallons
of water, may be used if infestations become severe.

TRUNK DAMAGE

Avocado Tree Girdler
Importance and Evidence of Infestation.-Larvae of the avo-
cado tree girdler, Heilipus apiatus Oliv., killed 8% of the trees

















Fig. 23.-Eggs in bark tissue, partially covered.
(Entire specimen 21/ millimeters wide.)







Insect Pests of the Avocado and Their Control 37

in one planting in 1947-1948, but have not been so injurious
since that time. Larvae feed in the inner bark of trees and
probably inflict there the most damage done by this insect.
Small trees (to six inches in diameter at ground level) are espe-
cially susceptible, since the inner bark is thin and larvae in the
more mature stages score the sapwood and in effect girdle the
trees. Larvae may be found in the crotches of branches but
are most common at ground level or just below. They also bur-
row in tissues of the upper and larger roots. Adults feed on
buds, bloom, twigs and young fruit, as discussed elsewhere.
Reddish colored frass is extruded by the larvae from the feeding
burrows and is observed near ground level. This is a usual indi-
cation of infestation.
Description.-Larvae are white and range from 1/20 to about
/4 inch in length (Fig. 23). Larger, more mature larvae are
more likely to be observed than the eggs or smaller larvae.
Larvae transform to pupae (Fig. 24 ), then to adults in the bark
and wood of infested trees. Adult specimens range from about
2/ to 9/10 inch long. The general overall color is black with
irregular patterns of white scales on the sides of the beetles.
This insect has a prominent beak or snout, characteristic of
most weevils.
Control.-Two or more annual examinations of tree bases
for frass is recommended indicate larval infestations. Excision


















Fig. 24.-Larva and pupa of the avocado tree girdler (much enlarged).







38 Florida Agricultural Experiment Stations

of larvae from the trees, followed by painting the wounds with
a good tree wound paint, is recommended. Chemical treatments
have been tried, some with promise, some with indifferent re-
sults, but are not yet recommended.

Termites
Importance and Evidence of Infestation.-Small plants, seed-
lings, newly planted and mature trees may be infested with a
damp-wood termite, Neotermes castaneus (Burmeister) (identi-
fled by Dr. E. Morton Miller) (Figs. 25, 26). These infestations
are usually in the trunk (stem) but may be in the roots. Al-
though losses from termites are usually infrequent and minor,
they may cause young trees to wilt and die and older trees may
be unthrifty and low in vitality. Examination of the internal
parts of stems and branches of infested trees may reveal the
presence of termites or their galleries. Infestations may be
found any time of year.

























Fig. 25.-Termite infestation in trees recently set in field,
with sawdust mulch.






Insect Pests of the Avocado and Their Control 39










%I




























Fig. 26.-Termite infestation in mature avocado tree. Cracked, shrunken
bark shown in lower part, galleries in excised part of branch.







40 Florida Agricultural Experiment Stations

Description.-Winged forms of the termites are slightly
more than 12 inch long, soldier forms about 13 inch. Termites
have "thick waists" (i.e., have no constriction between thorax
and abdomen) and similar fore and hind wings.
Control.-Removal and destruction of the infested trees
and branches is recommended for large trees. For young trees
sprinkle one-half cup of a dust containing 5% chlordane, 21/2%
aldrin, 21/2% heptachlor or 11/2% dieldrin around the base of
young trees. Apply these materials only to the soil.

ROOT DAMAGE

Avocado Tree Girdler
Importance and Evidence of Infestation.-Larvae of the avo-
cado tree girdler, Heilipus apiatus Oliv., discussed elsewhere
(see pages 29, 31 and 36), are often taken below ground level
feeding in the roots of trees. They sometimes enter an exposed
root and destroy its tissues.
Description.-See page 37.
Control.-It is recommended that semi-annual examinations
be made of the tree trunks and bases and that larvae found be
destroyed. Heavy knives with straight thick blades are useful
for digging in the burrows, especially on the roots. Tree wound
paint may be applied to the knife wounds.

Little Fire Ant
Importance and Evidence of Infestation.-The little fire ant,
Wasmannia auropunctata (Roger), commonly infests groves. It
stings and bites workmen, carries scale insects and mealybugs
and removes soil particles from the roots of nursery and grove
trees. Its greatest damage is probably by removal of soil par-
ticles from the roots, permitting them to die. Presence of the
ants may be indicated by nests, or mounds of soil particles be-
side or near the trees. Presence of the ants may also be de-
tected by the biting and stinging actions.
Description.-The little fire ant worker is about 1/15 inch
long and reddish brown. When the colony or nest is disturbed,
the active workers swarm from the nest to bite and sting any
intruder. Although the little fire ant is present throughout the
year, it is usually more noticeable in late summer.







Insect Pests of the Avocado and Their Control 41

Control.-Parathion applied for scale control will control the
little fire ant. Ants nesting around the base of a tree may be
killed by applying chlordane, aldrin, heptachlor or dieldrin as a
dust, spray or granules to the ant hills and soil around the base
of the tree. Large areas may be treated by applying heptachlor
or dieldrin granules at the rate of 2 pounds active ingredient
(20 pounds of 10% granules) per acre. The material should be
broadcast evenly over the soil surface with a hand seeder or
similar equipment. These inseticides can be applied also in fer-
tilizers at the same rate of active ingredient. Apply these ma-
terials only to the soil.


FRUIT DAMAGE

SMALL, VERY YOUNG

Mirids
Importance and Evidence of Infestation.-Small plant bugs of
a number of species (see page 29) feeding in flower clusters may
also feed on very young fruit. Such feeding may cause some
fruit to fall and other fruit to be pimpled and deformed.
Description.-See page 29.
Control.-See page 29.

Webbing Caterpillars
Importance and Evidence of Infestation.-Masses of bloom
debris are held together by webbing secreted by larvae of Argy-
rotaenia amatana (Dyar) or other caterpillars. These larvae
feed on bloom, bloom pedicels and very young fruit (Fig. 27).
Such fruit may fall or be scarred and unmarketable.
Description.-See page 30.
Control.-See page 31.

Citrus Root Weevil
Importance and Evidence of Infestation.-Adults of the citrus
root weevil, Pachnaeus litus (Germ.), sometimes feed on very
young fruit. Such feeding is similar to that of the avocado tree







42 Florida Agricultural Experiment Stations

girdler (Fig. 28), but not as extensive. The beetle must be
recognized at the wound to be positive as to the infestation.
Description.-See page 16.
Control.-See page 17.



























Fig. 27.-Results of Argyotaenia amatana feeding on fruit
(upper left) and twig terminal (lower right).

Avocado Tree Girdler
Importance and Evidence of Infestation.-Adults of the avo-
cado tree girdler feed on very young avocado fruit (Fig. 28).
Such fruit may fall. Damaged fruit may remain on the tree,
mature and carry scars to market or cull bin.
Description.-See page 37.
Control.-See page 37.







Insect Pests of the Avocado and Their Control 43







Or-r




















Fig. 28.-Cavities in small (1/ to 1 inch diameter) avocado fruit
from avocado tree girdler (enlarged). Beetle on fruit at right.

LARGE (MORE THAN 1/ INCH IN DIAMETER),
MATURING

Greenhouse Thrips
Importance and Evidence of Infestation.-Within the last
three years increasing amounts of fruit have been scarred and
made culls from infestations by greenhouse thrips, Heliothrips
haemorrhoidalis (Bouche). These insects tend to congregate
and feed on the larger and more mature fruit, rather than grow-
ing fruit. They are found most frequently where two fruits
contact one another or where a leaf contacts the fruit. Discolor-
ation of the fruit surface and the presence of thrips are early
signs of infestation, followed by slight russetting (Fig. 29), then
by cracks in the fruit that widen and deepen and at last by
decay. All stages of the insect may be found on the fruit.







44 Florida Agricultural Experiment Stations



































Fig. 29.-Fruit scarring by greenhouse thrips (normal size).

Description.-Adult thrips are whitish for a very short time
after emerging from the pupal stage, but become black (Fig. 30).
They run rapidly, have fringed-wings and are about 1/20 to
1/25 inch in length. Eggs are deposited beneath the epidermis
of fruit or leaves. Slightly yellowish nymphs with red eyes
hatch from the eggs and are approximately 1/100 inch in length.
Control.-Constant vigil is recommended to determine the
presence or absence of infestations, beginning in early August
and continuing until fruit harvest. See Red-Banded Thrips for
control measures.







Insect Pests of the Avocado and Their Control 45


























Fig. 30.-Adults of greenhouse thrips (enlarged about 25 times).

Fruit Scarring Worms
Importance and Evidence of Infestation.-Some avocados
are culled because of damage from feeding by different worms.
Two tortricid moths are common, Platynota stultana Wlsn. and
Argyrotaenia amatana (Dyar). These scar both small, unde-
veloped fruit and mature fruit (Fig. 31). Cracks develop in the
wound which permit decay organisms to enter the fruit. Obser-
vations suggest that the amount of feeding by this insect has
been increasing within the last decade. Since the worms are
present for several months during the late growth and maturity
of the fruit, control of the pest is difficult. Scars suggest deep
russetting, but consist of rind excavations from the fruit sur-
faces, usually where surfaces of two fruits contact one another
or where a leaf adheres to the fruit. Depths of feeding may be
almost superficial or extend through the rind to the flesh of
the avocado. Scar area may cover as much as three square






46 Florida Agricultural Experiment Stations

inches and be covered with light to moderate webbing woven
by the larvae (Fig. 14).















.p0








Fig. 31.-Larvae of a fruit-scarring worm, showing
webbing and scarred tissue.

Description.-Larvae near maturity are about 1/2 inch in
length and are grayish, yellowish or brownish green. The
adults, seldom observed in the field, have wing spreads of about
one inch. The wings are medium brown to light yellowish
brown.
Control.-Lead arsenate, 3 pounds, or parathion, 1 pound of
15% wettable powder per 100 gallons of water may be used.

Pumpkin Bug
Importance and Evidence of Infestation.-The pumpkin bug,
Nezara viridula (L.), feeds on bloom and mature or nearly ma-
ture avocado fruits (Fig. 32) and permits decay organisms to
enter and cause spoilage. Although only minor losses are at-
tributed to this insect, it becomes very abundant at times.







Insect Pests of the Avocado and Their Control 47

Description.-These greenish bugs range in size from about
1/4 to 3/4 inch across the body and are the most common bugs in-
festing the avocado fruit. Nymphs (young of the species with
black areas and spots on its thorax instead of wings) and adults
frequently congregate on a single fruit.
Control.-Parathion, 11/2 to 2 pounds of 15% wettable pow-
der per 100 gallons of water, will control the pumpkin bug.

































Fig. 32.-Pumpkin bugs feeding on avocado fruit (about natural size).

Bagworm
Importance and Evidence of Infestation.-Bagworm larvae,
Oiketicus abbotii Grt., feed on fruit. Such feeding is more ex-







48 Florida Agricultural Experiment Stations

tensive on leaves (see page 12) than on fruit. Where bagworm
larvae are abundant, however, they feed on bloom and on younger
fruit. Since the larger fruit are exposed for a longer period, they
suffer more damage. Bagworm feeding is limited to the epi-
dermis. Such feeding removes protective covering from the
fruit which cracks open (Fig. 33) and permits decay organisms
to enter and destroy or make a cull of the fruit. Bagworm
larvae constitute positive evidence of infestation.
Description.-See page 13.
Control.-See page 13.

























Fig. 33.-Fruit scarred by feeding of bagworm.

Sooty Mold
Importance and Evidence of Infestation.-Sooty mold is a
black, unsightly, flaky material frequently covering leaves,
stems, branches, trunks and fruit. Film coverings of sooty mold
undoubtedly impair food manufacturing processes conducted by
leaves. It dulls the appearance of fruit and lowers its grade








Insect Pests of the Avocado and Their Control 49

for the market. Higher standards of grading the fruit for mar-
ket are currently more important than in previous years.
Description.-Excretory products from insects falling on
leaves, stems, branches, trunks and fruit afford a medium for
fungal growth. Such growth becomes black and remains on
leaves, bark and fruit for weeks and months. Excretory prod-
ucts come from scale insect, whitefly, aphid, mealybug and leaf-
hopper populations living on the tree.
Control.-Control of sooty mold results from control of insect
populations living on the trees. Elimination of sooty mold from
trees occurs through weathering, i.e., wind, rain, drying. Spray-
ing of trees with streams of water remove some of the sooty
material. Detergent added to the water increases the effective-
ness. Oil, 3 to 6 quarts per 100 gallons of water, added to the
water is also believed to assist in cleaning plants of the objec-
tionable black covering.


INSECTS INJURING OR ANNOYING TO
GROVE WORKMEN

Wasps
Importance and Evidence of Infestation.-Wasps, Polistes
sp., in protecting their nests, attack and sting fruit pickers.
Much time is lost in examining trees for nests, avoiding those
observed and destroying them in order to pick the fruit. Nests
and attendant wasps are found under overhanging branches
(Fig. 34). Nests are frequently hidden by leaves, making their
detection difficult.
Description.-Wasps are reddish brown with yellowish mark-
ings on the thorax and abdomen and with black membranous
wings. The insects are about 11/4 inches long. One or more
wasps may be found on each nest, ready to attack an invader.
Control.-If one nest per 2 to 25 trees is observed, destroy
the individual nests; but if a third to a half of the trees contain
nests, a grove application is suggested. A small, piston-type
hand sprayer containing a household spray mixture will eradi-
cate wasps on individually treated nests. Malathion, 3 pounds
25% wettable powder; parathion, 1 pound 15 % wettable powder;
or benzene hexachloride, 2 pounds 10% gamma-isomer wettable







50 Florida Agricultural Experiment Stations

powder per 100 gallons of water is suggested as a general grove
spray.
Mosquitoes
Importance and Evidence of Infestation.-Time is lost by
grove workmen in fighting mosquitoes, Aedes taeniorhynchus
(Wied.), Psorophora confinnis (L.-Arr.) and other species,
which would be spent otherwise in performance of their duties.
On occasions mosquito abundance prevents workmen entering
groves which delays harvesting fruit. Biting activity is evi-
dence of infestation.
Description.-These dark gray insects, about /4 to 1/2 inch
long, may infest groves and fly to attack workmen in the vicinity.
Control.-General grove spray, dust or thermal aerosol treat-
ments of groves are suggested for mosquito control. Sprays of
malathion, 3 pounds of 25% wettable powder or benzene
hexachloride, 2 pounds 10% gamma-isomer wettable powder or
lindane, 1 pound of 25 % wettable powder per 100 gallons of wa-
ter per acre are recommended.

Fig. 34.-Wasp nest in avocado tree.












4W.







Insect Pests of the Avocado and Their Control 51


MIXING, TIMING AND APPLICATION OF SPRAYS

It is economical to combine and apply as many materials for
pesticidal and nutritional purposes as is practicable. Costs of
application usually exceed costs of the materials. It is necessary,
however, to apply each of the materials at appropriate times.
Whenever two or more materials are needed at the same time,
consideration may be given to the combination. Combinations
of the generally recommended insecticides, fungicides and nutri-
tional materials usually function as effectively as if each were
applied separately. An exception to this generalization is that
of combining oil emulsion and sulfur, as reported on page 33.
Although many combinations are usually practiced, they cannot
be generally recommended since (1) not all combinations have
been tested and observed, (2) changes may be made in the man-
ufacture of those formulations tested and (3) climatic or other
conditions may be different from those previously observed.
Although avocado trees are tolerant of most pesticides, it
is evident that they are near the threshold of injury by some
chemicals. Oil emulsions of 11/2% oil may injure trees if applied
during a very cold, dry period or a hot (900 F.) period. It is
suggested, therefore, that recommendations concerning dosage
and time of application be followed.
Results of spray treatments may be ineffective because of
a number of factors. Mature larvae and pupae, commonly found
in severe infestations, for example, may continue to live after
an insecticidal treatment, whereas younger larvae succumb to
exposure to the toxicant. Only partial (90 to 97%) control of
the dictyospermum scale may be expected, even under favorable
conditions.
It is recommended that DDT not be applied to avocado trees.
Scale insects and mite increases, however, would likely result
from repeated applications of DDT, owing to the reduction of
predaceous or parasitic insects.
It is recommended that a miticide be combined with mal-
athion or parathion wherever they are applied to the trees in
the dry season (December through February).








AVOCADO PESTICIDE RECORD

Method- Pesticide Amount
Date of Acres Spray, and Amount Per Per Acre Remarks
Application Treated Dust Formulation 100 Gallons (Active)

EXAMPLE

3/15/63 5 Spray Malathion 4 Lbs. 10 Lbs. Mites bad; scales building up, etc.
25% W.P.







' '*





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